(Beyond Pesticides, June 27, 2014) The Environmental Protection Agency (EPA) is considering a request by Texas regulators to allow the use of a controversial herbicide, propazine, to battle Palmer amaranth, a glyphosate-resistant “super weed” that has been plaguing growers of genetically engineered (GE) herbicide-tolerant cotton in the state. Propazine, an active ingredient in Milo-Pro, would be sprayed on up to 3 million acres, which amounts to approximately half of the state’s estimated crop acreage for this season. As currently proposed, the maximum amount of product to be applied would be 70,314 gallons.
The Texas Department of Agriculture, on behalf of chemical-intensive GE cotton growers, asked EPA last month for an exemption to permit growers to spray fields with the herbicide this summer in order to control this highly invasive plant, also known as pigweed. Pigweed can grow up to 3 inches a day and is one of many plant species that has developed a resistance to glyphosate, a systemic herbicide found in Roundup that has become one of the most widely used pesticides on the market. Public comments are due by July 3, 2014.
The occurrence of super weeds coincides strongly with the use of toxic herbicides on genetically engineered (GE) crops. According to one study, “Impacts of genetically engineered crops on pesticide use in the U.S. ”” the first sixteen years,” author Charles Benbrook, Ph.D. writes that the emergence and spread of glyphosate resistant-weeds is strongly correlated with the upward trajectory of herbicide use. This makes Texas’s push to use propazine all the more troubling, as it would contribute to a “pesticide treadmill,” or positive feedback loop, generating new super weeds and necessitating the use of increasingly more toxic chemicals to control them. Emergency exemptions have already been granted to compensate for the failure of glyphosate-tolerant, Roundup Ready (RR) crops. EPA allowed the unregistered use of the herbicide fluridone on GE cotton in order to battle pigweed back in Arkansas in 2012. More disturbingly, Dow Chemical has been promoting its 2,4-D-tolerant corn and soybean varieties to replace RR crops. Subsequently, the use of 2,4-D, a highly toxic herbicide, on these GE crops has been estimated to increase 1.75-3 times current use, with independent estimates much higher.
A number of environmental groups, including Beyond Pesticides, oppose the propazine proposal on the basis that the pesticide presents a potential risk to human health. Propazine is a restricted-use pesticide that requires a license to purchase and apply, according to Milo-Pro’s manufacturer. Propazine is also closely related to atrazine, an herbicide used by corn growers that is banned in the European Union. A number of studies conducted by Tyrone Hayes, Ph.D., of the University of California, Berkeley, cite that atrazine can disrupt sexual reproduction in certain frog species. Studies that investigated the effects of subchronic and chronic exposure to propazine found that a variety of animal species were shown to exhibit neuroendocrine effects resulting in both reproductive and developmental consequences that are considered relevant to humans. In 1989, EPA classified propazine as a Group “C” (possible human carcinogen) chemical on the basis of “significant increases in mammary gland adenomas and adenomas/carcinomas in female Sprague-Dawley rats. The EPA used the Q1* approach with Q1*= 4.45 x 10-2 based on the Multi-Stage Weib model using a 3/4 scaling factor” (EPA Pesticide Fact Sheet, 1998). More than 15 years later, EPA reversed this classification. The Agency had received mode of action data on the ability of atrazine to induce mammary tumors in rats through the neuroendocrine mechanism of toxicity the chemical shares with propazine, which lead to the conclusion that the events leading to tumor formation are species/strain specific and therefore not operative in humans. As a result, EPA reclassified atrazine in 2000 as “not likely to be carcinogenic to humans.” Propazine was similarly reclassified in 2005 on the evidence that it is not genotoxic and operates via a mode of action for mammary and pituitary tumor development in female rats similar to atrazine. Interestingly enough, the California Environmental Protection Agency’s Office of Environmental Health Hazard Assessment (OEHHA) has issued a notice of intent to list propazine and atrazine under Proposition 65, which requires the state to regulate chemicals known to cause cancer, birth defects, or other reproductive harm and forces manufacturers to label their products to warn consumers.
Pursuing sustainable alternatives can prevent the pesticide treadmill that results from the overuse of GE crops and pesticides like propazine. Integrated pest management strategies, organic practices, and solutions that are not chemical-intensive would be the most appropriate and long-term solution to battling pigweed. Additionally, organic agriculture is an ecologically-based management system that prioritizes cultural, biological, mechanical production practices, and natural inputs. By strengthening on-farm resources, such as soil fertility, pasture and biodiversity, organic farmers can minimize and even avoid the production challenges that most genetically engineered organisms have been falsely-marketed as solving. To learn more about organic agriculture, see Beyond Pesticides Organic Program Page.
Please consider submitting public comments against the issuance of this emergency exemption by July 3, 2014.
Learn more about toxic pesticides and their effects on health by checking out Beyond Pesticide’s Pesticide-Induced Diseases Database. You can also read more about genetic engineering, including latest news, here.
Source: The Wall Street Journal, EPA
All unattributed positions and opinions in this piece are those of Beyond Pesticides